Material conveyance system in a combine harvester

ABSTRACT

A combine harvester is provided with a conveyance system for transporting crop material discharged by overhead grain separating apparatus to a grain cleaning shoe. The conveyance system comprises a series of oscillating pans which move the grain in a generally longitudinal direction. A return pan conveys the collected material forwardly to a front discharge edge from where the material falls onto a stratification pan below. The stratification pan conveys the collected material rearwardly to a rear discharge edge from where the material falls into the grain cleaning shoe. At least one of the return pan and the stratification pan is non-rectangular and has a non-transverse discharge edge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/420,896, filed May 23, 2019, which is a divisional of U.S. patentapplication Ser. No. 15/567,341, filed Oct. 17, 2017, which is a U.S.National Phase application of International Patent ApplicationPCT/EP2016/057665, filed Apr. 7, 2016, and published in English as WO2016/166016 A1 on Oct. 20, 2016, which claims priority to U.K. PatentApplication GB 1506557.6, filed Apr. 17, 2015, the disclosure of each ofwhich is hereby incorporated by reference in its entirety.

FIELD

The invention relates to combine harvesters and particularly to materialconveyance systems employed by such to move crop material separated bygrain separating apparatus to a grain cleaning shoe.

BACKGROUND

Self-propelled combine harvesters have been used by farmers since theearly twentieth century to harvest grain crops from fields. Since thenthe basic architecture of the crop processing system employed has notchanged significantly and is well known.

FIG. 1 illustrates in schematic form the main components of the cropprocessing system of a combine harvester 10 and will be used to explainthe flow of material below. The crop processing system is shown in solidlines whilst the outline profile of harvester 10 is shown in ghost form.It should be appreciated that the details of combine 10 described beloware by way of example only and the following description thereof servesonly, at this stage, to provide background on the general operatingprincipals of a combine harvester.

Combine harvester 10, hereinafter referred to as ‘combine,’ includes aframe 12 supported on front wheels 14 and rear steerable wheels 16 whichengage the ground 101. A driver's cab 18 is also supported on the frame12 and houses a driver's station from where a driver controls thecombine 10.

A cutting header 20 is detachably supported on the front of afeederhouse 22 which is pivotable about a transverse axis x to lift andlower the header 20 in a conventional manner.

The combine 10 is driven in a forward direction (arrow F) across a fieldof standing crop 102 in a known manner. The header 20 serves to cut andgather the standing crop material before conveying such as a cropmaterial stream into feederhouse 22. An elevator 24, normally in theform of a chain and slat elevator as shown, is housed within thefeederhouse 22 and serves to convey the crop material stream upwardlyand rearwardly from the header 20 to the crop processor designatedgenerally at 26. At this stage the crop material stream is unprocessed.

The crop processor 26 of the illustrated combine 10 includes a pair ofaxial flow threshing and separating rotors 28 fed by a tangential flow,crop material impelling, feed beater 30.

The feed beater 30 rotates on a transverse axis and comprises cropengaging vanes (not shown) which convey the crop material stream underthe beater and into rotor housings 32 which each house one of saidrotors 28. It should be appreciated that only the left-hand rotor 28 andhousing 32 is shown in FIG. 1 whereas the right-hand equivalent ishidden from view.

The rotors 28 are positioned to have a generally longitudinal, or foreand aft, rotation axis which is normally inclined upwardly towards therear of the combine 10.

Flighting elements (not shown) provided on the front end of each rotor28 engage the crop material stream which is then conveyed as a ribbon ormat 103 in a generally rearward axial and helical path in the spacebetween the rotor 28 and the rotor housing 32.

Axial flow rotors 28 serve to thresh the crop stream in a front region,separate the grain therefrom in a rear region, and eject the strawresidue through an outlet 34 in the housing 32 at the rear of themachine either directly onto the ground in a windrow 104 as shown, orvia a straw chopper (not shown).

A part-cylindrical grate 36 provided in the underside of each rotorhousing 32 allows the separated material to fall by gravity onto eithera return pan 38 located below a rear section of the processor 26, ordirectly onto a stratification pan 40 located below a front section ofthe processor 26. In reality the separated material falling through thegrate 36 is typically a mix of grain and material other than grain (MOG)which may include chaff, tailings and some straw.

The twin rotor axial flow processor 26 shown is one example of knowncrop processors employed in combines today. Other known, and wellestablished, types of crop processors include single rotor axial flowprocessors, tangential flow/straw walker (or conventional) processors,and hybrid processors.

The return pan 38 and stratification pan 40 together serve as a materialconveyance system arranged to convey the separated crop material to agrain cleaning shoe designated generally at 42. The pans 38, 40 eachinclude a respective linkage (not shown) to convert a torque source intooscillating motion to oscillate the pans in a generally fore and aftdirection. Combined with a transversely rippled or corrugated floor, theoscillating movement of the return pan 38 and stratification pan 40propels the material generally forwardly or rearwardly respectively.

The return pan 38 “returns” the separated material incident thereontowards the front of the combine 10 (in the direction F) to a frontdischarge edge from which the material falls or cascades onto thestratification pan 40. The material on the stratification pan 40 isconveyed rearwardly to a rear discharge edge 46 from where the materialfalls into the cleaning shoe 42.

The grain-MOG mixture conveyed by the stratification pan 40 “stratifies”over the course of conveyance wherein the heavier grain works its wayinto a bottom grain-rich layer and the lighter MOG works its way into atop MOG-rich layer. This pre-stratification effect upstream of thecleaning shoe has been found to be beneficial to the overall cleaningprocess and the capacity of the shoe. Moreover, extending the return pan44 forwardly to present a significant overlap with the stratificationpan 40 (even more so than shown) has been found to enhance thestratification of the total grain-MOG mix. The effects and advantages ofpre-stratification of the grain-MOG mix is disclosed in InternationalPatent Application Publication WO 2012/095239, the contents of which isincorporated herein by reference.

The pre-stratified grain-MOG mix falls from the rear discharge edge 46into the cleaning shoe 42 where the cascading mix is subjected to acleaning airstream generated by fan unit 48, before falling onto thefront of upper sieve or chaffer 50.

Chaffer 50 comprises adjustable louvres supported on a frame which isdriven in fore-and-aft oscillating manner. The material which settles onthe chaffer 50 is conveyed in a generally rearward direction and theheavier smaller grain-rich material passes between the louvres onto anunderlying lower sieve 52, whereas the lighter larger material passes tothe end of the chaffer and out of the rear of the machine at 54. A rearsection of chaffer 50 a is commonly independently adjustable and isconfigurable to allow un-threshed tailings to pass therethrough into are-threshing region 56 from where the tailings are conveyed via are-threshing auger 58 back to the processor 26.

Lower sieve 52 is also driven in an oscillating manner to convey thecollected grain-MOG mix rearwardly wherein the material fallingtherethrough is collected by a clean grain auger 60 for conveyance to anelevator (not shown) for onward conveyance to a grain tank 62. Materialwhich does not pass through lower sieve 52 and is instead conveyed offthe rear edge thereof falls into re-threshing region 56 for subsequentre-threshing.

The airstream generated by fan unit 48 is also conveyed by ducting upthrough lower sieve 52 and chaffer 50 to encourage lifting of the MOGfrom the chaffer surface.

For completeness the combine 10 includes an unloading system whichincludes an unloading auger 64.

Ever since the introduction of the self-propelled combine harvester andthe well-known crop processing architecture embodied therein, the trendhas been for machines having greater capacity with time. Upsizing of thevarious constituent systems has been the obvious route to increasingcapacity such as wider cutting headers, wider cleaning shoes and highercapacity grain tanks. However, today high-capacity machines are upagainst the size limit in terms of maximum width and height imposed byhighways legislation. Manufacturers are, therefore, faced with thechallenge of increasing capacity without breaching the existing spatialmachine envelope.

One bottleneck in the drive for increased capacity in the cropprocessing architecture today is the limitations presented by thematerial conveyance system between the processor and the cleaning shoe.Any further increase in throughput without an increase in total machineheight and/or width will lead to a significantly raised occurrence rateof blockage simply due to the finite space available between theoverlapping material conveyance pans.

BRIEF SUMMARY

In accordance with the present invention there is provided anon-rectangular crop material conveyance pan for a combine harvester.The conveyance pan may be, for example, a return pan, a stratificationpan or a cascade pan for use in a combine harvester conveyance system.

Reference to the shape of the crop material conveyance pan is made inrelation to the profile of the major surface or pan floor when viewedfrom above. Conventional crop material conveyance pans in combines arerectangular with two long parallel sides and two shorter parallel sides,one of which forms a material discharge edge. A non-rectangularconveyance pan in accordance with the invention provides a longereffective discharge edge thereby spreading out the material and reducingthe risk of blockage.

The crop material conveyance pan may comprise three edges with amaterial retaining lip or profile and a crop discharge edge which has atleast a portion which is non-orthogonal with respect to the adjacentsides. Preferably the pan comprises a pair of opposite parallel sidesfor alignment with the sides of the internal profile of a combine. In asimple embodiment, the crop material conveyance pan is trapezium-shaped(European definition of trapezium) with one pair of parallel sides andone pair of non-parallel sides.

A combine harvester in accordance with an embodiment of the inventioncomprises the crop material conveyance pan which, by way of example, maybe a return pan or a stratification pan in a crop material conveyancesystem for transferring crop material separated by grain separatingapparatus to a grain cleaning device or “shoe.”

A combine harvester embodying the invention shall have a normal forwarddirection of travel which defines a longitudinal direction and atransverse direction for the purposes of defining further embodiments ofthe invention. It should be understood that the transverse direction isperpendicular to the longitudinal direction, wherein a transverse axisextends horizontally from left to right of the combine harvester.

When installed in a combine harvester, the crop material conveyance panis coupled to a drive mechanism which is operable to drive the pan in anoscillating or reciprocating manner, wherein the pan is positioned inthe combine harvester so that the discharge edge is disposed at anon-zero angle to a transverse vertical plane.

Advantageously, by angling the discharge edge with respect to thetransverse direction, a longer discharge edge can be accommodatedwithout having to increase the width of the pan nor the width of theenvelope which houses such. It shall be appreciated that the cropmaterial transported by the conveyance pan is deposited by the dischargeedge in a line which is spread longitudinally, rather than in a straighttransverse line across the width of the pan. Such longitudinal spreadingof the deposited material delivers beneficial effects which will bedescribed in more detail below in relation to preferred embodiments.

In one embodiment the discharge edge of the crop material conveyance panextends from a first side edge to a second opposite side edge. Thedischarge edge may be straight or curved or include both straight andcurved portions. The discharge edge is longer than the transverse widthof the pan as defined by the normal forward direction of the combine.

In some preferred embodiments said crop conveyance pan is a return panpositioned under the grain separating apparatus, the return pan servingto catch crop material separated by such and convey the collectedmaterial in a generally forward direction to the discharge edge.

It is recognized that the spacing between the discharge edge of a returnpan and the surface below onto which the conveyed material is depositedis finite. Furthermore, the scope to increase this spacing is limited bythe aforementioned restrictions on total machine height. As mentionedabove, this finite window for the crop material to pass through presentsan increased risk of blockage in association with any increase inthroughput. By angling the discharge edge of the return pan with respectto the conventional transverse direction, the passage available for thewindow is increased thus reducing the risk of blockage and easing therestrictions on increasing material throughput.

The combine harvester may further comprise an oscillating grain pan,hereinafter referred to as a “stratification pan”, positioned to catchcrop material falling from the discharge edge of the return pan, andconvey the crop material rearwardly to a grain cleaning shoe. Thedischarge edge of the return pan preferably resides entirely over thestratification pan so that all of the grain-MOG mix caught by the returnpan has an opportunity to stratify on the stratification pan beforebeing presented to the cleaning shoe.

The return pan and/or the stratification pan preferably comprises acorrugated or ‘rippled’ floor with a saw-tooth profile to assist inconveyance of the crop material in conjunction with the oscillatingmotion. Moreover, the return pan and/or the stratification pan may beinclined longitudinally so as to offer a general incline or decline inthe longitudinal direction. Such an angle is selected depending on thearchitecture of the harvester and the available space, as well as thedesired crop conveyance rate.

It should be understood that a crop material conveyance pan inaccordance with the invention will be preferably unperforated andcomprise a major upward-facing surface or “floor” over which the cropmaterial is conveyed. References made herein to the angle or incline ofthe crop conveyance pan in accordance with the invention are made inrelation to the angle of the material conveying floor thereof.

In a first set of preferred embodiments having a return pan with anon-transverse edge, a transverse vertical section of the return pan ishorizontal. It is understood that the return pan may be sloped in thelongitudinal direction, typically downhill in the general forwarddirection of material conveyance, as is common in combines today. Inthis first set of preferred embodiments at least one transverse sectiontaken through the return pan is horizontal. In other words, materialresting upon the return pan floor (with the combine on flat ground),naturally flows, aided by gravity and the oscillating motion, in adirection that is longitudinally forward but with a negligibletransverse component. Such a return pan is preferably planar over amajority of the floor surface, albeit with a rippled floor profile.

The profile of the discharge edge of the return pan in accordance withpreferred embodiments of the invention is dependent upon the type andlayout of the grain separating apparatus disposed above. The inventioninvolves the recognition that the profile of the grain-MOG dischargedfrom the separating apparatus, and collected by the stratification andreturn pans, is far from uniform often leading to a significantly unevenwidth-wise distribution of the material both in terms of the grain-MOGratio and the volume of material. A suboptimal distribution of the grainand MOG on the stratification pan can result in reducedpre-stratification whilst an imbalance in material volume across thewidth of the stratification pan is known to result in poor cleaningefficiency.

In one simple embodiment of the invention, the grain separatingapparatus comprises an axial-flow crop processing rotor having arotation axis which is aligned fore and aft, the rotor having adown-turning side and an up-turning side, and wherein the discharge edgecomprises a forward edge zone and a rearward edge zone disposed rearwardof the forward edge zone, and wherein the forward edge zone residesbelow the down-turning side of the rotor, and wherein the rearward edgezone resides below the up-turning side of the rotor.

It has been observed that such an axial-flow processor tends to deposita higher proportion of separated material on the down-turning side thanon the up-turning side thus leading to a lateral imbalance of materialcaught by the return pan and the stratification pan. Moreover, thematerial discharged on the down-turning side is more grain-rich byvolume whereas material discharged on the up-turning side is moreMOG-rich by volume.

By providing a forward, or leading, edge zone laterally correspondingwith the down-turning side of the rotor above, the grain-rich material,and the majority of the grain, collected by the return pan is depositedonto the stratification pan at a positon that is more forward than thedischarge location of the MOG-rich material collected by the return pan,albeit laterally offset. Advantageously, a greater proportion of thegrain caught by the return pan is carried to the front of thestratification pan thus giving the grain and longer transit path on thestratification pan thus enhancing pre-stratification whilst alsobenefitting from the discharge edge of increased length.

The above-described embodiment with a planar, non-laterally sloping,return pan can be adapted to cater for a twin axial-flow crop processor.In such an arrangement, the grain separating apparatus comprises a pairof axial-flow crop processing rotors having respective rotation axeswhich are aligned fore and aft and mutually side-by-side, and whereineach rotor has a down-turning side and an up-turning side, wherein therotors are driven to rotate in opposite directions defining transverselyinner up-turning sides and outer down-turning sides, and wherein thedischarge edge comprises a central rearward edge zone and forward edgezones disposed forwardly, and to each side of, the rearward edge zone,and wherein each forward edge zone resides below the down-turning sideof one of the rotors, and wherein the rearward edge zone resides belowboth up-turning sides.

By way of example, the discharge edge may be curved from one side to theother in a generally concave fashion or straight with a V-shapedprofile. Again, the higher proportion of grain falling from thedown-turning side of the two rotors is carried further forward fordeposition onto the stratification pan than the material falling fromthe up-turning sides.

In an alternative arrangement in which the direction of rotation of therotors is the reverse of that described above (down-turning on theinside), the discharge edge comprises a central forward edge with anadjacent pair of rearward edges.

Enhanced pre-stratification can be achieved with the provision of a dualreturn pan arrangement in which first and second oscillating return pansare positioned under the grain separating apparatus, longitudinallyoffset from one another and each serving to catch crop materialseparated by such and convey the collected material in a generallyforward direction to a respective discharge edge. This arrangement, perse, is described in International Patent Application PublicationWO-2015/062965. In short, the dual return pan arrangement exploits theuneven longitudinal grain-MOG distribution profile falling fromseparating apparatus to deposit a high-proportion of the grain-richmaterial onto the front of the stratification pan with a front returnpan, whilst the MOG-rich material from the rear of the separatingapparatus is delivered to the rear of the stratification pan (on top ofthe grain) by a rear return pan.

The present invention can be applied in conjunction with such a dualreturn pan arrangement wherein at least one of the return pans comprisesa non-transverse discharge edge. In such an arrangement with planarreturn pans.

Advantageously, the above-described embodiments of the invention aresimple to implement in today's combines by small changes in the designof the return pans. For example, one need only adapt the profile of thedischarge edge to extend the effective length of such and derive some ofthe aforementioned benefits.

It is recognized that the above-described simple embodiments do notassist significantly in the lateral balancing of the grain-MOG materialcollected by the return pan. In a second set of preferred embodimentsthe return pan comprises a transversely, or laterally, inclined floorportion in combination with a non-transverse discharge edge.

The return pan preferably comprises a contoured floor portion whichguides crop material sideways under gravity to a trough, wherein thedischarge edge comprises a forward edge zone and a rearward edge zonedisposed rearward of the forward edge zone, and wherein the troughguides crop material to the forward edge zone. By providing a laterallysloping floor portion the material collected on parts of the return pancan be steered laterally. In conjunction with the non-transversedischarge edge, this material can be deposited on the stratification panfor optimal pre-stratification and for optimal width-wise loading of theshoe.

This aspect of the invention further involves the recognition that thegrain-MOG mix conveyed on the return pan stratifies to some extent overits transit. By laterally shifting the material on the return pan thetransit path is increased thus increasing the stratification. Moreover,the troughs defined by the sloping floor portions enhance suchstratification as the heavier grain sinks to the bottom of the troughswhilst the lighter MOG works to the top of the material mat. When thestratified mat reaches the front of the return pan, the transverselyangled discharge edge serves to carry the bottom layer of grain furtherforward onto the stratification pan than the layer of MOG sitting ontop. As shall be appreciated, this enhances pre-stratificationimmediately upstream of the cleaning shoe.

As with the first set of embodiments, the chosen profile of thenon-transverse discharge edge is dependent upon the type and arrangementof the grain separating apparatus disposed above. Moreover, the contourprofile of the laterally sloping floor portions and troughs is alsodependent upon the type and arrangement of the grain separatingapparatus disposed above.

A return pan having a laterally sloping floor portion in conjunctionwith a non-transverse discharge edge can be employed in combines havingvarious different types of separating apparatus, and for single or dualreturn pan configurations.

By way of example, a combine having grain separating apparatuscomprising a single axial-flow rotor, preferably has a return panwherein the forward edge zone resides below the up-turning side of therotor, and wherein the rearward edge zone resides below the down-turningside of the rotor. The laterally inclined floor portion of the returnpan serves to guide the grain-MOG material collected under thedown-turning side toward the up-turning side and deposit this materialtoward the front of the stratification pan. Whilst passing over thereturn pan, the grain and MOG stratify so that the upper MOG-richmaterial falls from the return pan at a position further back comparedto the lower grain-rich material.

Furthermore, the lateral incline is exploited to laterally redistributethe high volume of material falling from the down-turning side of therotor. The rearward positioning of the discharge edge on thedown-turning side in this arrangement, advantageously allows thegrain-rich material falling from the front of the separating apparatusto fall directly onto the stratification pan.

It shall be appreciated that the profile of the discharge edge withrespect to the up-turning and down-turning sides of the rotor in thisarrangement is in contrast to that for the equivalent planar return pandescribed above. This is because the laterally sloping floor portion ofthe return pan facilitates lateral redistribution of the collectedmaterial whereas a planar pan with no lateral incline does not.

The above-described embodiment can be adapted to cater for a twinaxial-flow crop processor. In such, the contoured floor portion slopesaway transversely from a catchment portion disposed below thedown-turning side of each rotor defining at least one trough below theup-turning side of each rotor. In the case of both rotors up-turningtoward the center of the combine, the return pan floor preferablycomprises a central longitudinal trough so that material collected underthe respective down-turning (outer) sides is steered laterally towardthe center vertically stratifying all the while. In such an arrangement,the discharge edge preferably comprises a rearward edge zone on bothsides of a central forward edge zone so as to allow the material fallingfrom the down-turning sides at the front of the separating apparatus tofall directly onto the stratification pan thus laterally balancing thewidth-wise material distribution.

In a further embodiment of the invention, the combine comprises a dualreturn pan configuration wherein at least one of the return panscomprises a transversely inclined floor portion and a non-transversedischarge edge. Preferably, both the first and second return pans insuch an arrangement comprise a transversely inclined floor portion and anon-transverse discharge edge.

When a dual return pan arrangement is employed under separatingapparatus having a single axial-flow rotor, a floor portion of the frontreturn pan preferably slopes laterally downwardly to the down-turningside of the rotor, and a floor portion of the second return pan slopestransversely downwardly to the up-turning side of the rotor.

When a dual return pan arrangement is employed under separatingapparatus having a twin axial-flow rotor setup, the front return panpreferably comprises sloping floor portions which are each inclinedlaterally and downwardly towards a zone below the up-turning side of therotors, and the second return pan comprises sloping floor portions whichare each inclined laterally and downwardly towards a zone below thedown-turning sides of the rotors. In other words, for a pair ofseparating rotors which turn upwardly in the middle, the grain-MOG mixcaught by the front return pan is guided toward the transverse center ofthe combine, whereas the grain-MOG mix caught by the rear return pan isguided outwardly.

The floor of front return pan preferably comprises a centrallongitudinal trough, and the floor of the second return pan preferablycomprises a central longitudinal crest.

Advantageously, a dual return pan arrangement provides improvedlongitudinal distribution of the grain and MOG on the stratificationpan, wherein the contour and discharge edge profiles of the return panscan be adapted to cater for different grain separating apparatusconfigurations.

The front return pan may have a non-transverse rear edge so as to,advantageously, increase the discharge window for material discharged bythe rear return pan thus reducing the risk of blockage. In a preferredarrangement a gap is provided, when viewed from above, between the rearedge of the front return pan and the front edge of the rear return pan,through which grain and MOG can fall directly from the separatingapparatus above onto the stratification pan below.

Advantageously, a dual return pan arrangement occupies less height undergrain separating apparatus than a single return pan of equivalent lengthdue to the longitudinal (downhill) incline required for adequateconveyance. However, in a combine where height availability is less ofan issue then a single return pan in accordance with a preferredembodiment can be employed wherein the floor of the return pan comprisesan opening which defines a secondary discharge edge. The secondarydischarge edge, offset rearward of the front discharge edge, serves inpart a similar function to the discharge edge of a rear return pan in adual return pan arrangement wherein a portion of the collected materialis discharged onto a rear zone of the stratification pan.

The floor is preferably contoured so as to define a material guidancetrough configured to guide crop material around the opening. Forexample, when applied together with twin rotor grain separatingapparatus the opening is preferably disposed intermediate a rear floorportion and a front floor portion, wherein the rear floor portioncomprises a central longitudinal crest, and wherein the front floorportion comprises a central longitudinal trough.

Advantageously, a single return pan with a secondary, intermediate,discharge edge consists of fewer components than a dual return panarrangement, albeit at the cost of increased height.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the invention will become apparent from readingthe following description of specific embodiments with reference to theappended drawings in which:

FIG. 1 is a schematic sectional view of a combine harvester having aknown crop processing architecture;

FIG. 2 is a schematic perspective view of a crop material conveyancesystem in a combine harvester in accordance with a first embodiment ofthe invention;

FIGS. 3 and 4 are schematic plan and sections views respectively of thecrop material conveyance system of FIG. 2 ;

FIG. 5 is a schematic perspective view of a crop material conveyancesystem in a combine harvester in accordance with a second embodiment ofthe invention;

FIG. 6 is a schematic plan view of the crop material conveyance systemof FIG. 5 ;

FIG. 7 is a schematic perspective view of a crop material conveyancesystem in a combine harvester in accordance with a third embodiment ofthe invention;

FIG. 8 is a schematic sectional view of the crop material conveyancesystem of FIG. 7 ;

FIG. 9 is a schematic perspective view of a return pan in a combineharvester in accordance with a fourth embodiment of the invention;

FIG. 10 is a schematic plan view of the crop material conveyance systemof FIG. 9 ;

FIG. 11 is a schematic sectional view of the return pan of FIG. 10 takenalong the line XI-XI and showing the vertical stratification of grainand MOG;

FIG. 12 is a schematic perspective view of a crop material conveyancesystem in a combine harvester in accordance with a fifth embodiment ofthe invention;

FIG. 13 is a schematic plan view of the crop material conveyance systemof FIG. 12 ;

FIG. 14 is a schematic sectional view of the return pan of FIG. 13 takenalong the line XIV-XIV and showing the vertical stratification of grainand MOG;

FIG. 15 is a schematic perspective view of a crop material conveyancesystem in a combine harvester in accordance with a sixth embodiment ofthe invention;

FIG. 16 is a schematic plan view of the crop material conveyance systemof FIG. 15 ;

FIG. 17 is a schematic perspective view of a crop material conveyancesystem in a combine harvester in accordance with a seventh embodiment ofthe invention;

FIG. 18 is a schematic plan view of the crop material conveyance systemof FIG. 17 ;

FIG. 19 is a schematic perspective view of a crop material conveyancesystem in a combine harvester in accordance with a eighth embodiment ofthe invention; and,

FIG. 20 is a schematic plan view of the crop material conveyance systemof FIG. 19 .

DETAILED DESCRIPTION

The combine harvester depicted in FIG. 1 has been described above inrelation to the component architecture and the general crop materialflow through the combine. Reference is invited to the description above.Reference numbers used in FIG. 1 for the stratification pan 40, andcleaning shoe will be reused in the following embodiments.

The present invention relates to the material conveyance system disposedbelow the grain separating apparatus and employed to convey the grainand MOG falling therefrom to the cleaning shoe 42. Although aspects ofthe invention can be applied to the stratification pan 40, or a cascadepan, the specific embodiments described hereinafter involve applicationof the present invention to the return pan 44, or a return pan system,for conveying the collected material forwardly in the direction F.

Relative terms such as forward, rearward, transverse, lateral,longitudinal, and sideways will be made with reference to the normalforward direction of travel of the combine 10 and indicated by arrow F.The terms vertical and horizontal will be made with reference to thelevel ground 101 upon which the combine 10 is disposed. In other wordsthe Cartesian axes of ‘longitudinal’, ‘transverse’, and ‘vertical’ aremade in relation to the frame 12 of combine 10 and are not affected byany slope in the ground. The terms “upstream” and “downstream” are madewith reference of the general direction of crop flow along the materialconveyance systems described.

Planar Return Pan

In a first embodiment illustrated in FIGS. 2, 3 and 4 , a crop materialconveyance system 100 comprises a return pan 138 and a stratificationpan 40. It should be understood that the conveyance system 100, andfurther systems to be described, can replace the return pan 38 andstratification pan 40 of the combine 10 described with reference to FIG.1 .

Both the return pan 138 and stratification pan 40 are coupled to a drivemechanism (not shown) for driving the respective pans in an oscillatingmanner. The pans 138, 40 are disposed below grain separating apparatus126 which, in this example, comprises a single axial flow cropprocessing rotor having a rotation axis X₁ which is aligned fore-and-aftand transversely centered. The grain separating apparatus 126 isrepresented schematically (in dashed lines) to reveal the underlyingconveying system 100.

It should be understood that although referred to as grain “separating”apparatus, the axial flow processing rotors described in the followingembodiments may additionally serve a threshing function. For example, afront portion of the processing rotor may comprise threshing elementswhereas a rear portion of the rotor comprises separating elements.

As will now be apparent from reading the above description, the materialconveyance system 100 serves to collect grain and MOG discharged by thegrain separating apparatus 126 and convey the collected material to thecleaning shoe 42. As in known systems the return pan 138 conveys thecollected grain and MOG forwardly to a front discharge edge 144 fromwhich the material falls onto the underlying stratification pan 40 whichthen conveys the material rearwardly to a rear discharge edge 46. Aswill be apparent from FIG. 4 , grain and MOG falling from the front ofseparating apparatus 126 falls directly onto stratification pan 40.

Return pan 138 is mounted inside the envelope of combine 10 so as to beinclined downwardly towards the front end so as to exploit gravity forforward conveyance of the collected material. As with known return pans,the major, upward facing, surface thereof defines a floor which mayinclude a rippled or corrugated surface profile which assists inconveyance of the material. The return pan 138 is trapezium-shapedhaving a first long side 171, a second shorter side 172 opposite thefirst long side 171, a rear edge 173 and a front discharge edge 144which is aligned at a non-zero angle θ₁ to a hypothetical transversevertical plane indicated in FIG. 3 by dashed line T₁. The twolongitudinal sides 171,172 and the rear edge 173 are provided with amaterial retaining lip 174 whereas the front discharge edge 144 is opento allow material to fall therefrom.

Discharge edge 144 is disposed at an angle θ₁ to the transversedirection or to a transverse vertical plane T₁. As a result theeffective discharge edge has a length w′ which is longer than the widthw of pans 40, 138. Although the height h between the discharge edge 144and the underlying stratification pan 40 remains the same, the increasein length of the effective discharge edge w′ increases the windowthrough which material can pass between the pans 40, 138 thus reducingthe risk of blockage and/or allowing for increased material throughput.

As has been described above, axial-flow grain separating apparatusdischarges a higher volume of material on the down-turning side d thanthe up-turning side u, as is the case with single rotor processor 126illustrated. The transverse angle θ₁ of the discharge edge 144 is suchthat material incident on down-turning side dis carried further forwardonto stratification pan 40 than material incident on up-turning side u.This is illustrated in FIG. 3 . Grain and MOG falling on down-turningside d is conveyed generally forwardly as shown by arrows D to a firstforward edge zone z₁ of discharge edge 144 from where the material fallsonto the stratification pan 40. Grain and MOG falling onto up-turningside u is conveyed forwardly and longitudinally as indicated by arrows uto a second, rearward, edge zone z₂ which is disposed rearward (towardsthe rear of the combine) than forward edge zone z₁.

It is recognized that the high volume of material falling ontodown-turning side d has a higher grain-to-MOG ratio than the materialfalling onto upward turning side u. Advantageously, the grain-richmaterial on the down-turning side d is carried further forward onto thestratification pan 40 thereby increasing the transit path thereof andincreasing the opportunity for the grain on the stratification pan 40 tosettle to the bottom layers before being presented to the cleaning shoe42. This is in contrast to the more MOG-rich material on the up-turningside u which falls from rearward edge zone z₂ towards the rear ofstratification pan 40 and onto the top of grain already settled thereonhaving falling directly from the front end of grain separating apparatus126.

In a second embodiment illustrated in FIGS. 5 and 6 , theabove-described angled discharge edge is applied to a grain conveyancesystem 200 disposed below a twin-rotor, axial-flow, grain separatingapparatus having rotors 226 represented by dashed lines. In theembodiment illustrated, and as is common with twin rotor systems, thegrain separating rotors rotate in opposite directions as indicated byarrows R wherein the sides adjacent the longitudinal center line of thecombine turn upwardly and the sides nearest the outside of the combineturn downwardly. The rotation axes of rotors 226 are illustrated in FIG.6 by lines X_(R) and X_(L). The rotation directions of the rotors 226define a central up-turning zone u and two outer down-turning zones d.

The grain conveyance system 200 comprises a return pan 238 and astratification pan 40, the latter having the same rectangular profile tothat described above.

Focusing on the differences with respect to the first embodiment, thedischarge edge 244 comprises a central rearward edge zone z₃ and forwardedge zones z₄, z₅ disposed forwardly and to each side of the rearwardedge zone z₃. It should be understood from FIG. 6 that the rearward edgezone z₃ resides below the up-turning zone u of rotors 226 whereas eachforward edge zone z₄, z₅ resides below the respective down-turning zonesd. Adopting the same principles as in the first embodiment, the highvolume of grain-rich material falling on the down-turning sides d isconveyed forwardly to forward edge zones z₄, z₅ whereas the moreMOG-rich material falling on up-turning side u is discharged onto thestratification pan 40 further back.

Discharge edge 244 is predominantly curved having a concave-shapedprofile when viewed from above. However, it should be understoodalternative profiles can be employed whilst still embodying theinvention, wherein the edge zone z₃ corresponding to the up-turning zoneu is disposed rearward of the edge zones z₄, z₅ corresponding to thedown-turning zone d. It should also be understood that the embodiment ofFIGS. 5 and 6 can be adapted for grain separating rotors which turn indifferent directions to those shown.

It will be appreciated that the effective discharge edge 244 is longerthan the width of the pans 40, 238 and, as a result, the risk ofblockage is reduced whilst increasing the capacity of higher materialthroughput.

In a third embodiment (FIGS. 7 and 8 ) a material conveyance system 300comprises a dual return pan system and a stratification pan 40. Theprinciple of a dual return pan is described in International PatentApplication Publication WO 2015/062965 A1, wherein two separate returnpans are employed one behind the other, each having respective frontdischarge edges. A rear return pan 338 is disposed under a rear portionof twin rotor separating apparatus 226 and has a similar constructionand floor profile to that of return pan 238 described in the previousembodiment. A second, front, return pan 378 is located in front of therear return pan 338 and serves to collect grain and MOG from a frontportion of the separating apparatus 226.

In short, the dual return pan system exploits the recognition that themajority of the grain discharged by the separating apparatus 226 fallsfrom a front portion. The front return pan 378 collects this high volumeof grain rich material and conveys this to a front region ofstratification pan 40 whereas the rear return pan 338 collects materialricher in MOG and discharges such onto a rear region of thestratification pan. As a result, a higher proportion of the separatedgrain has an increased transit path on the stratification pan thusincreasing the effect of stratification upstream of the cleaning shoe42. The MOG-rich material discharged from the discharge edge 344 of rearreturn pan 338 falls onto the grain layers on a rear region ofstratification pan 40 thus enhancing the stratification further.Furthermore, the dual return pan system spreads the total volume ofmaterial falling from the separating apparatus 226 thus reducing therisk of blockage and increasing potential throughput capacity.

As can be seen from FIG. 7 , both the front and rear return pans 378,338 have a respective discharge edge 380, 344 which includes a centralrearward edge zone corresponding to the up-turning side of separatingrotors 226 and forward edge zones located either side of the rearwardedge zones. The effective length of each discharge edge 344, 380 isincreased as per the above-described embodiments thus reducing the riskof blockage. Furthermore, the grain-rich material falling on thedown-turning sides of the separating rotors 226 is conveyed furtherforward onto the stratification pan 40 than the material falling ontothe up-turning side.

The discharge edge 380 of the front return pan 378 has a substantiallyV-shaped profile whereas the discharge edge 344 of rear return pan 338is curved. It should be understood that the profiles of the dischargeedges are shown merely by way of example.

In an alternative (not illustrated) embodiment, the rear edge of frontreturn pan 378 may be shaped so as to have a concave-shaped profilewhich present a larger ‘window’ to material falling from the front edge344 of the rear return pan 338, thus reducing the risk of blockage andimproving capacity thereof.

The return pan, or pans, of the above-described embodiments each have asubstantially planar floor, albeit corrugated for assisting materialconveyance. Advantageously, implementation of such return pans, andtheir associated benefits, into today's combine models is relativelystraightforward and simply requires adaptation of the profile of theleading discharge edge without any requirement to adapt the drivemechanism or substructure of the pan.

Contoured Return Pans

In a further aspect of the invention the return pan may be mountedinside the combine so as to have a transversely inclined floor portionwhich, with the assistance of gravity, imparts a sideways or lateralforce on the conveyed material so as to shift the material sideways asit is conveyed forwardly to the discharge edge. Such action can beexploited to laterally distribute the collected grain and MOG to achievea more balanced distribution of crop material in terms of volume on thestratification pan and ultimately across the width of the cleaning shoe.

Employed in conjunction with an angled discharge edge as describedabove, the contoured floor portion preferably guides the crop materialsideways to a trough which guides the material to a forward edge zonefor reasons which will become apparent below.

A fourth embodiment is depicted in FIGS. 9, 10 and 11 . A single rotor,axial-flow, grain separating apparatus similar to that shown in FIG. 4has a central longitudinal rotation axis X₁ shown in FIG. 10 and whichdefines a down-turning side d and an up-turning side u. (The separatingapparatus is omitted from FIGS. 9,10 and 11 for reasons of clarity.) Ashas been mentioned above, a significant proportion of the grain and MOGdischarged by the separating apparatus falls from the down-turning sided. Furthermore, a higher proportion of the material volume falls fromthe front of the separating apparatus than the rear. With reference toFIGS. 9 and 10 , a significant proportion of the grain falls from thefront end of the down-turning side d directly onto zone ‘A’ ofstratification pan 40.

Return pan 438 has a front discharge edge 444 which is angled withrespect to a transverse vertical plane so as to provide a forward edgezone z₆ and a rearward edge zone z₇. As best seen in FIG. 10 , theforward edge zone z₆ resides under the up-turning side u of theseparating apparatus whereas the rearward edge zone z₇ resides under thedown-turning side d. (This is in contrast to the embodiment of FIG. 3involving a planar return pan).

A significant proportion of the floor of return pan 438 is transverselyor laterally inclined so as to form a lateral angle θ₂ with thehorizontal, represented by dashed line L in FIG. 11 . In the embodimentshown the entire length of the floor of return pan 438 is transverselyinclined. However, in alterative embodiments only portions of the floorare inclined.

Grain and MOG incident on the down-turning side d of return pan 438 isguided sideways and forwardly by the slope of the return pan 438 and theoscillating motion thereof towards a trough 482 residing on theup-turning side u. This is represented in FIGS. 9 and 10 by zone ‘B’ andby arrows D.

Trough 482 is aligned fore and aft and guides grain and MOG to theforward edge zone z₆ on the up-turning side u. Advantageously, the grainand MOG collected by the return pan 438, the majority of which iscollected on the down-turning sided, is shifted laterally by the slopingreturn pan 438 to the up-turning side u thus laterally balancing thevolume of separated material on the stratification pan 40, andultimately in the cleaning shoe 42.

The transit of grain and MOG across the floor of stratification pan 438leads to some degree of vertical stratification with the heavier grainsinking to the floor whilst the lighter MOG rises to the top. Thestratification of grain and MOG on the return pan 438 is enhanced by theprovision of trough 482 wherein, as shown in FIG. 11 , grain G comes toreside in the bottom of the trough 482 with MOG M resting on top. Due tothe transverse inclination θ₂ a lateral spreading of the MOG-rich upperlayers occurs as shown in FIG. 11 .

The grain-rich lower layer is discharged from the forward edge zone z₆whereas only MOG is discharged from the rearward edge zone z₇. Due tothe transversely angled discharge edge 444 the grain G is depositedfurther forward on the stratification pan 40. The MOG-rich materialfalling from the rearward edge zone z₇ falls on top of the grain thatwas incident on zone A and has settled on the pan. As a result thestratification of grain and MOG on stratification pan 40 is enhanced.

In a fifth embodiment (FIGS. 12, 13 and 14 ) the previous embodiment isadapted for use under a twin-rotor, axial-flow, grain separatingapparatus similar to that shown in FIG. 5 but omitted from the drawingsin this case for reason of clarity. The two grain separating rotaryprocessors have rotation axes indicated as X_(R) and X_(L) and arelocated above material conveyance system 500 which comprises a returnpan 538 and stratification pan 40. The rotation axes X_(R), X_(L)together define a central zone u extending longitudinally andcorresponding with the up-turning sides of the rotary processors, and apair of outer zones d extending longitudinally and corresponding to therespective down-turning sides of the rotors.

The floor of return pan 538 slopes away transversely from the outerzones d and towards a central longitudinal trough 582. A significantproportion of the grain and MOG falls onto outer zones d from where thematerial is conveyed forwardly and inwardly towards the trough 582 asindicated by arrows D. As in the previous embodiment, the grain G andMOG M stratify as the material is conveyed across the return pan 538.

FIG. 14 shows the grain-rich material G residing in the base of trough582 whilst the MOG M sits on top thereof. Due to the laterally-inclinedfloor the MOG layer M is laterally stretched leaving the grain focusedtowards the transverse center.

Front discharge edge 544 of return pan 538 has a V-shaped protrudingprofile with a central forward edge zone z₈ flanked by rearward edgesz₉, z₁₀. As in the previous embodiment, forward edge zone z₈ residesunder the up-turning sides u of the separating rotors whereas the outerrearward edge zones z₉, z₁₀ each reside under a respective down-turningside d. This is in contrast to the return pan located under a twin-rotorprocessor of the second embodiment shown in FIG. 6 .

The transverse extent of the respective edge zones z₈, z₉, z₁₀ aresuper-imposed on FIG. 14 . It can be seen that the majority of the grainG falls from the forward edge zone z₈ which is more forward on thestratification pan 40 than the MOG M falling from rearward edge zonesz₉, z₁₀. Advantageously, the grain G collected by return pan 538 isdisposed towards the front of the stratification pan 40 therebyincreasing the transit path thereof and thus the opportunity to stratifyupstream of the cleaning shoe 42.

The laterally spread MOG M falling from the rearward edge zones z₉, z₁₀falls onto a rearward zone of the stratification pan 40 thus on top ofgrain already settled on the pan. In addition to the advantageouslongitudinal spread of material on the stratification pan 40, thelateral incline of the return pan 538 deposits the grain G on to atransverse central zone of the stratification pan thus providing a morebalanced load thereon.

In a sixth embodiment (FIGS. 15 and 16 ) a material conveyance system600 comprises a stratification pan 40 and a dual return pan systemhaving a rear return pan 638 and front return pan 678. Both the frontand rear return pans 678, 638 have transversely-inclined floor portionswhich steer the collected grain and MOG sideways into a respectivetrough 682, 684.

The material conveyance system 600 in accordance with a sixth embodimentis configured to be used under a single-rotor axial flow grain processorhaving a rotation axis X₁. The floor of front return pan 678 slopestransversely downwardly to the down-turning side d of the rotor whilstthe floor of the rear return pan 638 slopes transversely downwardly tothe up-turning side u of the processing rotor.

Front return pan 678 has a transversely angled discharge edge 680 havinga forward edge zone z₁₁ on the down-turning side d and rearward edgezone z₁₂ on the up-turning side u. Grain and MOG caught by the frontreturn pan 678 is guided laterally to the forward edge zone z₁₁.Vertical stratification of the grain MOG thereon and the consequentiallateral spreading of the grain and MOG layers occurs on front return pan678 in a similar manner to that of the embodiments described above.

The design of the rear return pan 638 can be considered a mirror imageof the front return pan 678 wherein material caught thereby is laterallysteered into trough 682 disposed on the up-turning side u and leading toa portion discharge edge 644 that is displaced forwardly of the portionon the down-turning side d. The movement of material on rear return pan638 is indicated by arrows D.

The opposite transverse inclination of the floors of front and rearreturn pan 678, 638 improves the transverse distribution of cropmaterial in terms of load on the stratification pan 40 whilst alsoexploiting the advantages of a dual return pan system.

It should be noted from FIG. 16 that the rear edge 686 of frontstratification pan 678 is also transversely angled in the same directionas that of the front edge 680. When viewed from above a gap 688 existsbetween the rear edge 686 of the front return pan 678 and the front edge644 of rear return pan 638. This gap permits material to fall directlyfrom the processing rotor overhead directly on to the stratification pan40.

In a seventh embodiment (FIGS. 17 and 18 ) a material conveyance system700 is adapted to cater for a twin-rotor, axial flow, grain separatingprocessor and comprises a stratification pan 40 and a dual return pansystem having a front return pan 778 and a rear return pan 738.

The front return pan 778 has a floor which is transversely inclineddownwardly towards a central zone, or trough, 782 which resides underthe up-turning sides of the overhead rotors and corresponds to a centrallongitudinal zone u. The front discharge edge 780 comprises a centralforward edge zone z₁₃ flanked by rearward edge zones z₁₄, z₁₅.

Although shown as having a V-shaped profile, the discharge edge 780 maytake on many alternative forms including a stepped profile or a curvedprofile by way of example.

Forward edge zone z₁₃ corresponds to the zone u whereas the rearwardedge zones z₁₄, z₁₅ reside under respective down-turning sides d. Thecentral longitudinal trough 782 guides the collected grain and MOG tothe forward edge zone z₁₃ which deposits such material towards the frontof the stratification pan 40 in the center thereof. The rearward offsetof the outer portions z₁₄, z₁₅ of discharge edge 780 allows asignificant proportion of grain to fall directly from the separatingrotors above onto zones ‘A’ of the stratification pan 40.

Advantageously, the front return pan 778 serves to balance the volume ofmaterial on the stratification pan by depositing the majority of thecollected grain onto the central portion between zones A. Any materialdischarged from rearward edge zones z₁₄, z₁₅ is rich in MOG and is thusdeposited on top of the already-settled grain on stratification pan 40.

Rear return pan 738 comprises sloping floor portions which are inclinedtransversely and downwardly towards a pair of troughs 790 disclosedbelow the downward turning sides d. A central longitudinal crest 792 isalso provided in the profile of the floor of rear return pan 738. Grainand MOG collected by the rear return pan 738 is steered laterallyoutwardly into troughs 790 all the while stratifying wherein the graincomes to rest in the base of the troughs 790 and the MOG rises to thetop and spreads laterally outwardly due to the lateral slope of thefloor. The front discharge edge 744 of rear return pan 738 comprisesouter forward edge zones z₁₆, z₁₇ disposed either side of a centralrearward edge zone z₁₈ together forming an inward V-shaped profile. Thegrain collecting in the trough 790 is therefore deposited onto theunderlying stratification pan 40 further forward than the MOG which isdischarged by the rearward edge zone z₁₈ thus enhancing stratificationon the stratification pan 40.

The rear edge 786 of front return pan 778 has a cut-out section orrather has a concave-shaped profile which reveals a gap 788 when viewedfrom above. Advantageously, the gap 788 enlarges the window throughwhich material can pass from the discharge edge 744 of the rear returnpan 738 thereby reducing the risk of blockage.

In an eighth embodiment (FIGS. 19 and 20 ) the dual return pan systemdescribed above is configured as a single unitary return pan 838 for useunder a twin-rotor axial flow grain separating apparatus having rotationaxes X_(R), X_(L). The return pan 838 comprises a rear portion having alongitudinal central crest 892 and outwardly-inclined floor portionsleading to troughs 890, and a front portion having a longitudinalcentral trough 882 and inwardly-sloping floor portions. An opening 888is formed in the floor of return pan 838 between the rear portion andthe front portion. The opening 888 defines a secondary discharge edge894 from which material collected on the rear portion of the return pan838 can be discharged onto the underlying stratification pan 40.

Grain and MOG incident on the rear portion of return pan 838 is steeredlaterally outwardly away from the crest 892 and towards troughs 890. Thetroughs 890 guide the majority of the grain around the opening 888 ontothe front portion of return pan 838. Due to the lateral spread of MOG ontop of the grain, a portion of the MOG is caused to fall through theopening 888 onto a rear portion of the underlying stratification pan 40.The secondary discharge edge 894 has an inward V-shaped profile as perthe discharge edge 744 of the previous embodiment for the same reasons.

Grain and MOG incident on the front portion of return pan 838, togetherwith grain and MOG conveyed around the opening 888, is steered laterallyinwardly towards central trough 882 as shown by arrows Y. Frontdischarge edge 444 has a positive V-shaped profile similar to that ofdischarge edge 780 of the previous embodiment for the same reasons.

In summary, there is provided a combine harvester with a conveyancesystem for transporting crop material discharged by overhead grainseparating apparatus to a grain cleaning shoe. The conveyance systemcomprises a series of oscillating pans which move the grain in agenerally longitudinal direction. A return pan conveys the collectedmaterial forwardly to a front discharge edge from where the materialfalls onto a stratification pan below. The stratification pan conveysthe collected material rearwardly to a rear discharge edge from wherethe material falls into the grain cleaning shoe. At least one of thereturn pan and the stratification pan is non-rectangular and has anon-transverse discharge edge.

It should be emphasized that the above-described embodiments of thepresent disclosure are merely possible examples of implementation,merely set forth for a clear understanding of the principles of thedisclosure. Many variations and modifications may be made to theabove-described embodiments of the disclosure without departingsubstantially from the spirit and principles of the disclosure.

What is claimed is:
 1. A combine harvester having a normal forwarddirection of travel which defines a longitudinal and a transversedirection, the harvester comprising: a grain separating apparatus, agrain cleaning shoe having one or more sieves arranged to convey cropmaterial in a generally rearward direction, a crop material conveyancesystem arranged to transfer crop material separated by the grainseparating apparatus to the grain cleaning shoe, wherein the cropmaterial conveyance system comprises a crop material conveyance panhaving a discharge edge and an unperforated floor with a non-rectangularprofile as viewed from above, wherein the discharge edge is disposed ata non-zero angle to a transverse vertical plane, and wherein the cropmaterial conveyance pan is arranged to catch crop material separated bythe grain separating apparatus and convey the crop material in agenerally forward direction to the discharge edge.
 2. The combineharvester of claim 1, further comprising an oscillating grain panpositioned to catch crop material falling from the discharge edge of thecrop material conveyance pan, and convey the crop material rearward to agrain cleaning shoe.
 3. The combine harvester of claim 1, wherein thegrain separating apparatus comprises an axial-flow crop processing rotorhaving a rotation axis which is aligned fore and aft, the rotor having adownturning side and an upturning side.
 4. The combine harvester ofclaim 3, wherein the grain separating apparatus comprises a pair ofaxial-flow crop processing rotors having respective rotation axes whichare aligned fore and aft and mutually side-by-side, and wherein eachrotor has a downturning side and an upturning side.
 5. The combineharvester of claim 4, wherein the rotors are driven to rotate inopposite directions defining transversely inner upturning sides andouter downturning sides.
 6. The combine harvester of claim 1, furthercomprising first and second oscillating crop material conveyance panspositioned under the grain separating apparatus, wherein the first andsecond oscillating return pans are longitudinally offset from oneanother, wherein the first and second oscillating return pans are eachconfigured to catch crop material separated by the grain separatingapparatus and convey the collected material in a generally forwarddirection to a respective discharge edge, and wherein at least one ofthe first and second oscillating return pans has a non-transversedischarge edge.
 7. The combine harvester of claim 6, wherein the firstoscillating crop material conveyance pan is positioned under a frontportion of the grain separating apparatus and the second oscillatingcrop material conveyance pan is positioned under a rear portion of thegrain separating apparatus.
 8. The combine harvester of claim 6, whereinthe first and second oscillating crop material conveyance pans eachexhibit non-transverse discharge edges.
 9. The combine harvester ofclaim 6, wherein a rear edge of the first oscillating crop materialconveyance pan is positioned aft of, and higher than, at least a portionof the discharge edge of the second oscillating return pan.
 10. Thecombine harvester of claim 6, wherein a transverse section of at leastone of the first and second oscillating crop material conveyance pans ishorizontal.
 11. The combine harvester of claim 1, wherein the return pancomprises a transversely inclined floor portion.